Method for storing hydrogen in a subterranean gas storage cell

Abstract

A method of hydrogen storage and recovery includes injecting saline water into a subterranean gas storage cell in a subterranean geologic formation, including magnetite. The method further includes injecting a gas mixture having hydrogen gas at a positive pressure into the subterranean gas storage cell, and then storing a portion of the hydrogen gas in the magnetite under a storage condition. At least a portion of hydrogen is desorbed of the hydrogen gas from the magnetite by injecting a chelating solution into the subterranean gas storage cell.

The invention claimed is: 
     
       1. A method of hydrogen storage and recovery in a subterranean gas storage cell, comprising:
 fracking the subterranean gas storage cell in a subterranean geologic formation comprising magnetite to increase a porosity thereof; then 
 injecting saline water into the subterranean gas storage cell; 
 injecting a gas mixture comprising hydrogen gas at a positive pressure into the subterranean gas storage cell; 
 storing a portion of the hydrogen gas in the magnetite under a storage condition; and 
 desorbing a part of the portion of the hydrogen gas from the magnetite by injecting a chelating solution into the subterranean gas storage cell; 
 wherein the chelating solution includes at least one iron chelator selected from the group consisting of ethylenediaminetetraacetic acid (EDTA), ethyleneglycol-O,O′-bis(2-aminoethyl)-N,N,N′,N′-tetraacetic acid (EGTA), and N-(2-hydroxyethyl)ethylenediaminetriacetic acid (HEDTA). 
 
     
     
       2. The method of  claim 1 , wherein the chelating solution comprises EDTA. 
     
     
       3. The method of  claim 2 , wherein the chelating solution comprises 0.1-2.0 mol. % of EDTA. 
     
     
       4. The method of  claim 1 , wherein the saline water comprises ions of Na + , Ca 2+ , Mg 2+ , SO 4   2− , Cl −  and HCO 3   − . 
     
     
       5. The method of  claim 4 , wherein the saline water comprises, by mass, ions of:
 Na + : 5,000-50,000 parts per million (ppm); 
 Ca 2+ : 100-1,500 ppm; 
 Mg 2+ : 500-5,000 ppm; 
 SO 4   2− : 1,000-9,000 ppm; 
 Cl − : 10,000-90,000 ppm; and 
 HCO 3   − : 10-500 ppm. 
 
     
     
       6. The method of  claim 5 , wherein a volume of the saline water injected is 0.1-0.9 times of a volume the subterranean gas storage cell. 
     
     
       7. The method of  claim 4 , wherein the storage condition includes keeping the ions in the subterranean gas storage cell. 
     
     
       8. The method of  claim 1 , further comprising:
 injecting the saline water and the gas mixture at a depth in the subterranean gas storage cell such that the subterranean gas storage cell has an average temperature of 60-150° C., wherein 
 the storage condition includes the average temperature of 60-150° C. of the subterranean gas storage cell. 
 
     
     
       9. The method of  claim 1 , wherein the positive pressure is 100-2000 psi. 
     
     
       10. The method of  claim 1 , wherein the subterranean geologic formation comprises 70-100 mass % of magnetite based on a total mass of the subterranean geologic formation. 
     
     
       11. The method of  claim 1 , wherein the subterranean geologic formation comprises 50-90 mass % of Fe 3 O 4  based on a total mass of the subterranean geologic formation. 
     
     
       12. The method of  claim 11 , wherein the subterranean geologic formation further comprises 20-35 mass % of SiO 2  based on a total mass of the subterranean geologic formation.